Gripping device for sheet metal stretching machines



L. TINLEY GRIPPING DEVICE FOR SHEET Sept. 12, 1950 METAL STRETCHING MACHINES 3 Sheets-Sheet 1 Filed July 24, 1947 INVENTQR BY WJW E. L. TINLEY GRIPPING DEVICE FOR SHEET Sept. 12, 1950 METAL STRETCHING MACHINES 3 Sheets-Sheet 2 Filed July 24, 1947 #15 m ml 74 INVENTOR AT TORNEY.

Sept. 12, 1950 E. TINLEY 2,522,319

GRIPPING DEVICE FOR SHEET METAL STRETCHING MACHINES Filed July 24, 1947 3 Sheets-Sheet 5 ATTORNEY.

Patented Sept. 12, 1950 GRIPPING DEVICE FOR SHEET METAL STRETCH'ING MACHINES Ernest {Lambert ,Tinley, Wolverhampton, En

and, assignor to Joshua Bigwood .& Son Limited, Wolverhampton, England Apnlicaticn. Ju1y;24, 1947, Serial No. 763,270

- -In GteMBritain July 25 1946 {this inventionrelates to sheet metal stretchnsmachin s, t is well known connection wi large rolled sheets of metal that, .aiter rolling, stresses have been setup in the sheet, andcthat these stresses can be removed by a stretching operation. Such sheets maybe 20 it. long and 6 ft. wide up to of an inch thick and to remove the stresses a stretching :force of 400 tons or more may be required. v

To apply this strain it isessential that a poweriul grip on the two opposed edges of the sheet should be obtainedand in order toremove the stresses for the full widthof the sheets it is essential that the grip should be effective for the full width of the sheet notwithstanding variations in thickness and contou-rof ;the-sheet,-which obtain in practice withrolledsheetsthou h these variation are small, ,say up to /iooe-of an inch.

The invention remtes to stretching-machines for the above purpose in whi h two p osed gripping jaws are provided one r which is us,- ually stationary and the other receded by a hy draulic control which applies the strain.

The gripping devices used inthis type of ma chine usually com rise a pair of Jaws each havin a pair .of relatively inclined parts noon which the gripping jaws are mountedin such manner that as the strain increases so the grip is increased by the grippingmembers being closed by beingforced inwardly between -=th;e converging-in clines inthe jaws.

Ac ord n to this invention --.ea h gri is obtained by a pai f zsr npin memhers vatjl one of which extends continuously across the width of the work and is controlled by a closing device which distorts this gripping member in u h manner as to rip h sheeteon in o ly across its width notwithstanding the variation in thickness and contour which obtain in practice- The grip ing members-may take the form of opposed gripping barstatleast one of which {extends continuously across the Width .Of the work and is controlled by a fl id pr ure closing de- Vice for the purpose of distortingthis gripping bar.

The pp d p n bars may be suppo ed inside a recess in the main jaw member, said recess havin opp e ou w dlyconver ing,in? olined surfaces and atleast one of the gripping bars may be supported along it l n hin a p. rality of blocks. which are capable pf movement re ative to each otheralon one of the incline u iaoes of the jaw ins cha manner as to per-.- mit ,distortion of this gripping bar when encountering variation in thickness and contour .of hcsheet.

1-0 claims. (01. 24.9253) Referring to the drawings.

Figure l is a view in side elevatiqnof ash-set metal stretching machine embodying ripping jaws constructed in accordance with the present invention.

Figure 2 is anenlarged view of the right hand gripping jaw in Figure 1.

Figure 3 is a vi-ewin end elevationofthe grip ping jaw in Figure 2 in the direction in which the work enters.

Figure 4 is'a section on the line 4--.-. 4 in Fig ure ,2.

Figure 5 is van enlarged fragmentary section on h line 5:5 f th grippin l n F gure 3 showing the construction of the upper and lower ripping members;

Figure 6 is an enlarged section on the-ilineqfiwfi in Figure .2.

In the construction as shown in Figures 1 $06 the lower gripper consists of a "number of gripping blocks IE1 secured together and extending for the full width of :the machinesupported upon the lower inclined surface I! of the jaw, pref erably through the medium of rollers 12 and these blocks l0 carry the gripping member proper which is in the formlof a hardened steel member i3 having a serrated or roughened upper surface M adapted to engage with the undersuriace of the sheet, this serrated member it being rigidly secured to the blocks I!) as by headed screws I5. Although this gripping bar 13 is described as being in one piece it may consist of a "plurality of short lengths disposed end toend 0.17 ialternap tively the gripping blocks to may be constructed as one continuous block.

The upper grip blocks it are in short lengths, say six inches and the gripping bar i1 is mounted loosely in a slotin each of these grip blocks 15, the distortion of the bar being effected by a flex.- ible advancement of the grip blocks I6.

These grip bloc-k5 slidably supported beheath the upper incline-i 8 of the jaw and in close contact with each other and preferably again with interposed rollers 19 and-extending for the full Width of the machine, the control bar 2!],

being operated for the purpose .Qf opening-and closing the gripping device by means-of a compressedair device, which conveniently comprises a piston 2! :and piston rod :22 in a cylinder as generally indicated at 23, the-pistonrod 2:2 being .connected to the control bar 20 by means :of a

pin 1M. This control bar 20 is connected to the endgripping blocks 2,5 by links 25 so that when and the control bar 2!! is a compression spring 2'! so that when the control bar is pneumatically advanced each grip block is pushed forwardly through the medium of the spring 21 and thus forces the gripping bar ll into contact with the upper surface of the sheet. With variations in the thickness or contour of the sheet one portion or portions of the gripping bar I! will engage before the remainder of the bar engagesso that further movement of the corresponding grip block or blocks is resisted but the other grip blocks continue to advance pushing corresponding parts of the gripping bar forwardly and distorting it so as to provide a continuous grip on the sheet.

This gripping bar may be conveniently of hardened steel 1 ins. wide, 1 ins. deep, secured to each grip block by a screw 28 and spring washer in such manner as to leave freedom of movement between the bar and the gripping blocks, there being a small clearance of say e in. between the width of the slots in the gripping blocks [6 and the width of the gripping bar l7.

Conveniently each grip block if; may be secured to the control bar 20 by a headed screw 29 passing through the grip block and entering the control 'bar, this screw being free to slide through the grip block when the control bar 29 is advanced, the rear portion of the grip block it being recessed to receive the compression spring 2i.

The cylinder of the pneumatic gripping control 23 has its axis parallel to the upper incline l8 of the jaw member and so arranged that the gripping mechanism for the upper surface is held in contact with the upper incline l8, so positively opening the jaw when the mechanism is receded.

I The one gripping jaw 3th is preferably station ary when in use though provided with a pneumatically controlled gripping device 23 as previously described and the other jaw 39 adapted for sliding movement under hydraulic control such as the piston and cylinder arrangement generally indicated at 32. The stationary jaw 33 is, however, provided with screws 33 or other adjustment so that its position can be altered according to the length of sheet to be treated.

The main jaw member 3 1 is preferably a steel casting extending for the full width of the ma-- chine the two inclined surfaces H and i8 previously referred to, being constituted. by liner plates 35 and 38 of hardened steel secured to the main jaw by studs 3? and 38.

The upper liner plates 35 are preferably made in short lengths, i. e. of a less length than the grip blocks l6, Each grip block is cut away and provided at each end with an angle plate 3t presented upwardly and inwardly so as to overhang and engage with a cut away portion 49 of the upper surface of the liner plate 35 thereby providing'a sliding support for the grip blocks. The upper inclined surfaces of the gri blocks are recessed at 45 to receive a plurality of rollers 19, the ends of which are located by the angle plates 39;

The lower liner 3!? may be in a single piece extending for the full width of the machine or in shorter lengths, being provided at intervals on its upper surface with strips 42 which locate the supporting rollers l2 beneath the lower gripping member.

Means are provided for adjusting this, lower gripping member in relation to the jaw to enable the machine to be more effectively used with sheets of different thicknesses, such means consisting of screws 43 and distance pieces 44 passing through each lower gripping block and abutting against the part 45 of the main jaw.

The main jaw member 34 is provided with end cover plates 46 for retaining the grip members in place but cutaway at 4'! to permit the insertion of the sheet.

In practice the one gripping jaw 30 is adjusted along the machine according to the length of the sheet to be treated and the lower grip members are pre-set according to the thickness of the sheet. The sheet is then inserted between the gripping bars l3 and H and each upper gripping mechanism is then closed through the medium of the compressed air devices 23, the serrated gripping bars engaging with the upper and lower surfaces of the sheet, local variations in thickness and contour of the sheet resulting in some of the upper grip blocks I6 movin forward further than others, thereby distorting the upper gripping bars until they provide a continuous grip or substantially continuous grip throughout the full length of the jaws.

The hydraulic mechanism 32 is then operated so that the two jaws are separated and the initial grip obtained by the compressed air device is then taken over by the strain on the sheet which causes the upper and lower gripping members to travel along the convergin inclines so that the greater the strain applied for stretching ,the

metal, the greater will be the grip, the distortion of the gripping bars being maintained by reason of their initial engagement, the teeth on the gripping bars having entered the surfaces of the sheet.

What I claim then is:

1. In a gripping device for sheet metal stretch ing machines, a main jaw member having a re-- cess therein, a surface of said recess being inclined; a plurality of movable blocks arranged side by side across the width of the main jaw member and supported in sliding engagement with said inclined surface; a gripping member extending continuously across the width of the main jaw member and supported in said blocks, and means for distorting this gripping member in such manner as to provide a continuous grip across the width of the work.

2. In a gripping device for sheet metal stretch: v ing machines, a main jaw member having a recess" with opposing, outwardly converging inclined surfaces; a plurality of movable blocks arranged side by sideacross the width of the main jaw member and supported in said recess in sliding engagement with said inclined surfaces; opposed gripe ping members supported in said movable blocks one of'said gripping members extending continuously across the width of the main jaw member;

and means associated with the said continuous gripping member for distorting this member in such manner as to provide a continuous grip across the width of the work.

3. In a gripping device for sheet metal stretch-l ing machines, a main jaw member having a recess,

' the blocks connected therewith. V v I 4. In a gripping device for sheet metal'stre'tch ing machines, a main jaw member having a recess therein; opposed sets of movable blocks arranged side by side across the width of the main jaw member and supported in said recessya pair of gripping members supported each in one of said sets of blocks one of said gripping members extending continuously across the width of the main jaw member; a control bar connected to the set of blocks which supports the said continuous gripping member; spring means interposed between said blocks and the control bar, and means for actuating said control bar so as todisplace the blocks connected therewith in such manner as to distort the continuous gripping member supported in said blocks.

5. In a gripping device for sheet metal stretching machines, a main jaw member having a recess therein; opposed sets of movable blocks arranged side by side across the width of the main jaw member and supported in said recess; opposed gripping members supported in said blocks one of said gripping members extending continuously across the width of the main jaw member; a control bar associated with the set of blocks which supports the said continuous gripping member; links connecting the outermost blocks of said set to the control bar; spring means interposed be tween the remaining blocks of said set and the control bar; and means for actuating said control bar so as to displace the blocks associated there-- with in such manner as todistort the continuous gripping member supported in said blocks.

6. In a gripping device for sheet metal stretching machines, a main jaw member having a recess there; opposed sets of movable blocks arranged side by side across the width of the jaw member and supported in said recess; a pair of opposed gripping members supported in said blocks one of said gripping members extending continuously across the width of the main jaw member; a control bar associated with the set of blocks which supports the said continuous gripping member; means for actuating said control bar so as to displace the blocks associated therewith, such means comprising a rod connected to the control bar and a fluid pressure device adapted to actuate said rod so as to displace the blocks through the medium of the control bar.

'7. In a gripping device for sheet metal stretching machines, a main jaw member having a recess therein; opposed sets of movable blocks'arranged side by side across the width of the main jaw member and supported in said recess; a gripping member extending continuously across the width of the main jaw member and loosely mounted in one set of blocks; a gripping member fixed in the other set of blocks; and means for distorting the loose continuous gripping member in such manner as to provide a continuous grip across the width of the work.

8. In a gripping device for sheet metal stretching machines, a main jaw member having a recess therein; opposed sets of movable blocks arranged side by side across the width or the main jaw adjusting the other gripping member and supported in said recess; opposed gripping members supported in said blocks one of said grippingmembers extending continuously across the width of the main jaw member; means for distorting the said continuous gripping memher in such manner as to provide a continuous grip across the width of the work, and means for member in relation to the main jaw member in order to accommodate metal sheets of different thicknesses.

9. In a grippin device for sheet metal stretching machines, a main jaw member having a recess with opposed, outwardly converging, inclined surfaces; opposed sets of movable blocks supported in sliding engagement with said inclined surfaces; a gripping member loosely supported in one set of blocks; a gripping member fixed in the op-' posing set of blocks; a control bar associated with the blocks supporting said loose gripping member; links connecting the outermost blocks of said set to the control bar; spring means interposed between the remaining blocks of said set and the control bar; each of said remainin blocks having a headed pin passing therethrough, being slidable therein, and being secured to the control bar; a rod connected to said control bar, the axis of said rod being approximately parallel to the inclined surface engaged by said set of blocks; and means for actuating said rod so as to advance and retract the control bar causing movement of the associated blocks in such manner as to distort the gripping member supported therein when encountering variations in thickness and contour of the work, so as to provide a continuous grip across the width of the work. 10. In a sheet metal stretching machine, two opposed main jaw members; each jaw member having a recess therein; a plurality of movable blocks arranged side by side across the width of the main jaw member and supported in said recess, a pair of grippingmembers supported in said blocks, one of said gripping members extending continuously across the width of the main jaw member recess means for distorting the said continuous gripping member of each pair so as to obtain a continuous grip across the width of the work for each jaw; means for advancing and retracting one of said jaws with respect to the other jaw and means for adjusting the position of said other jaw in order to accommodate difierent lengths of work.

ERNEST LAMBERT TINLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,522,319 September 12, 1950 ERNEST LAMBERT TINLEY It is hereby certified that error appears in the above numbered patent requiring correction as follows:

In the grant, line 14, strike out the words of seventeen years; same line, after grant insert until July 5, 1966; in the heading to the printed specification; line 9, before 10 Claims. insert the following:

Section 1, Public Law 690, August 8, 1946. Patent expires July 5, 1966 and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of November, A. D. 1950.

THOMAS F. MURPHY,

Assistant Gammzlsszoner of Patents. 

